Conventionally, the lithium-ion battery using various carbon system materials, such as natural graphite, artificial graphite, amorphous carbon and mesophase carbon, and lithium titanate, a tin alloy, etc. as a negative electrode active material is put in practical use. Kneading a negative electrode active material, electrically conductive auxiliary agents, such as carbon black and the binder of resin, then preparing slurry, applying and drying on copper foil, and forming a negative electrode is performed.
On the other hand, aiming at high capacity, a negative electrode for lithium-ion batteries using a metal and an alloy with big theoretical capacity as a lithium compound, especially silicon and its alloy, as a negative electrode active material is developed. However, since the volume of the silicon which carried out occlusion of lithium ion expands up to about 4 times to the silicon before occlusion, the negative electrode using silicon as a negative electrode active material repeats expansion and contraction at the time of a charge-and-discharge cycle. Therefore, exfoliation of a negative electrode active material occurred and there was a problem that it was very short life, as compared with the negative electrode which consists of the conventional carbon system active material.
As a conventional manufacturing method of the negative electrode which uses silicon, the technique mechanically grinding silicon to several micro meter size, applying it with a conductive material and using it as a negative electrode material for lithium batteries is known (see the patent document 1).
As other conventional manufacturing methods of the negative electrode which uses silicon, there are a method of anodizing a silicon substrate and forming slots, such as a slit, a method of making minute silicon crystallize in the ribbon shaped bulk metal etc. (see the patent document 2).
Otherwise, the technique depositing the particles of polymers, such as polystyrene and PMMA, on a conductive substrate, and giving metal which can alloy with lithium by plating, removing the particles of polymers and then producing a porous object (porous body) of metal is known (see the patent document 3).
The technique which uses the thing equivalent to Si intermediate alloy which is an intermediate product of the present invention as a negative electrode material for lithium batteries is known (see the patent documents 4 and 5).
The technique which uses the thing produced by heat-treating this as a negative electrode material for lithium batteries is known (see the patent document 6).
In relation to this technique, the technique which elutes and removes element M completely by acid or alkali from Si alloy of Si and element M, which is produced by applying rapid solidification technique is known (see the patent document 7).
The technique which etches metallic silicon with fluoric acid and nitric acid is also known (for example, patent documents 8 and 9).